On March 24, First Lt. Kevin Corley allegedly arrived with a three-man team at a warehouse in the border city of Laredo, Texas, armed with two semiautomatic rifles, a combat knife and a .300-caliber bolt-action rifle equipped with a scope. The men believed they had been hired by the Zetas to carry out a contracted killing and raid of a rival drug trafficking group’s storehouse, and had been called to receive the final details of the assignment. What they didn’t know, however, was that they were targets of an elaborate sting operation organized by the US Drug Enforcement Administration (DEA).

For the past six months, Corley had been speaking with DEA agents posing as Zetas representatives, and had promised both to carry out “wet work” (a military euphemism for assassinations) for the cartel as well as equip and train Zetas members in military tactics. According to a federal indictment (.pdf), Corley claimed that his status as an active duty soldier made it easy for him to pilfer weaponry from his post in Colorado, and demonstrated this by providing the agents with bulletproof vests, training manuals and other stolen military equipment.

However, after receiving phony instructions from the undercover operatives in the warehouse, the four men found themselves surrounded by federal law enforcement officers. Although agents killed one of the suspects while attempting to make an arrest, the remaining three were taken into custody. Two other accomplices based in South Carolina were arrested in conjunction with the sting operation.

While the fact that six US citizens were so completely willing to work for the Zetas is disturbing, the most worrisome aspect of this case is the fact that all four members of the would-be “kill team” (with the exception of the individual killed by federal agents, who was a cousin of Corley’s) were either current or former members of the US military.

This is a troubling reminder that US military personnel are not immune to the kinds of incentives that lure their military counterparts in Mexico into joining the Zetas. The Zetas’ links to the Mexican military have been a trademark of the group since their early days working as the enforcement wing of the Gulf Cartel. Their original 31 founders were all ex-members of the Mexican special forces, and today the group is thought to have deeply penetrated the military in the states of Hidalgo, Chihuahua and Tabasco, as well as other parts of the country. As the drug gang’s trafficking networks have grown, they have expanded their recruitment pool to include members of security forces in Guatemala, Honduras, El Salvador and Nicaragua.

Until now, however, there was no hard proof evidence that the cartel was capable of hiring US-trained military professionals to carry out its work. These arrests show that there is a very real possibility of such a trend, no doubt sounding alarm bells for US drug enforcement agents already concerned about the prospect of “spillover violence” in the American southwest.

The case is especially relevant in light of the Federal Bureau of Investigation’s recent warnings that the US military is facing "significant criminal threat" from gangs within its ranks. In the 2011 National Gang Threat Assessment released in October, the FBI names some 50 criminal organizations that count both current and ex-soldiers among their members. The list includes the Zetas, as well as a handful of transnational street gangs such as Mara Salvatrucha (MS-13), Barrio 18 and Barrio Azteca. Although they represent only a tiny fraction of veterans and servicemen, the FBI cautions that many gang members enlist in order to “receive weapons and combat training that they may transfer back to their gang.” The report also notes an uptick in gang-related graffiti in military bases overseas.

This phenomenon is a threat not only to the US, but to other countries in the hemisphere as well. If enough members of transnational criminal organizations acquire military expertise in the US, there is a chance that they will share these skills with affiliate cells in other countries in the region, potentially giving them a leg up against local officials. As InSight Crime has pointed out, many gangs already have the organizational infrastructure in place to do so. Both of El Salvador’s largest “maras” (street gangs) got their start in US prisons, and still maintain a strong presence in major cities like Los Angeles and Washington, DC.

Despite these concerns, the US military is a long way from seeing the kind of criminal penetration that plagues the Mexican army. That all six members of the “Zetas” plot had been under surveillance for months and eventually apprehended is a testament to the success that US law enforcement has had in foiling such criminal endeavors. Even still, with the Zetas growing more and more sophisticated, the risk of infiltration grows greater, and the US military may need to step up its internal monitoring to prevent this.

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